The paper introduces TRAMA (Traffic-Adaptive Medium Access), a protocol designed for energy-efficient and collision-free channel access in wireless sensor networks. TRAMA reduces energy consumption by ensuring that unicast and broadcast transmissions do not collide and by allowing nodes to enter a low-power, idle state when not transmitting or receiving. The protocol assumes a time-slotted environment and uses a distributed election scheme based on traffic information to determine which node can transmit at each time slot. TRAMA is shown to be fair and correct, avoiding collisions and ensuring that idle nodes do not receive data. An analytical model is presented to quantify TRAMA's performance, which is verified through extensive simulations using synthetic and sensor network scenarios. The results indicate that TRAMA outperforms contention-based protocols (CSMA, 802.11, and S-MAC) and static scheduled-access protocols (NAMA) in terms of energy savings and end-to-end throughput.The paper introduces TRAMA (Traffic-Adaptive Medium Access), a protocol designed for energy-efficient and collision-free channel access in wireless sensor networks. TRAMA reduces energy consumption by ensuring that unicast and broadcast transmissions do not collide and by allowing nodes to enter a low-power, idle state when not transmitting or receiving. The protocol assumes a time-slotted environment and uses a distributed election scheme based on traffic information to determine which node can transmit at each time slot. TRAMA is shown to be fair and correct, avoiding collisions and ensuring that idle nodes do not receive data. An analytical model is presented to quantify TRAMA's performance, which is verified through extensive simulations using synthetic and sensor network scenarios. The results indicate that TRAMA outperforms contention-based protocols (CSMA, 802.11, and S-MAC) and static scheduled-access protocols (NAMA) in terms of energy savings and end-to-end throughput.